- The supertristeroids: Large, chiral, molecular bowls prepared by trimerization of pentacyclic steroidal ketones
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(Chemical Equation Presented) Robinson annulation of coprostanone (1) at the 2,3- and 3,4-positions gave two pentacyclic enones (7 and 10) that contain A/B-cis-fused ring junctions. Reduction of these enones gave the pentacyclic steroidal ketones 2α,3β- (8) and 2α,3α-(3′- oxocyclohexano)-5β-cholestane (9) and 4α,3β- (11) and 4α,3α-(3′-oxocyclohexano)-5β-cholestane (12). The structures of compounds 8, 9, and 11 were unambiguously established by X-ray analysis. TiCl4-promoted trimerization of compounds 8 and 11 gave the "supertristeroids" 4 and 5, respectively: large (C93) chiral, hydrocarbon clefts with C3-symmetric pockets approximately 12 A in diameter.
- Song, Qiuling,Ho, Douglas M.,Pascal Jr., Robert A.
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p. 4449 - 4453
(2008/02/05)
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- Synthesis and substance P receptor binding activity of androstano[3,2- b]pyrimido[1,2-a]benzimidazoles
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Several heterosteroids containing a dihydroethisterone skeleton were prepared and shown to displace substance P in a receptor binding assay. Further biochemical (kinetic and Scatchard analyses) and pharmacological evaluation (substance P-induced plasma extravasation and salivation in the rat) of a representative example in this series (5a) established that these compounds are competitive antagonists at the substance P receptor.
- Venepalli,Aimone,Appell,Bell,Dority,Goswami,Hall,Kumar,Lawrence,Logan,Scensny,Seelye,Tomczuk,Yanni
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p. 374 - 378
(2007/10/02)
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- Resolution of conflicting migratory reports in ring expansion of 3-keto steroids to oxygen and nitrogen
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The migration of C-2 and/or C-4 to O or N in the Beckmann, Schmidt, and Baeyer-Villiger reactions of 3-keto steroids has been studied with the aid of (13)Cmr spectroscopy.Authentic specimens of the eight possible lactone and lactam products from both 5α- and 5β-cholestan-3-one have been prepared; their physical properties and 13Cmr assignments are given.Seven ring expansion reactions reported to give only one product have been found to give both possible migration products.The much studied reactions of 5α-cholestan-3,6-dione and its derivatives have been reexamined.The results emphasize again the necessity of using 13C spectra both as an analytical tool and as the best criterion of purity in work with these molecules.
- Dave, Vinod,Stothers, J. B.,Warnhoff, E. W.
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p. 2666 - 2678
(2007/10/02)
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